Remove ppc32 support
The powerpc secondary arch team has disabled all ppc32 builds in koji for
F21 and beyond:
FESCo also recently said that dropped or new architectures must essentially
prove they have an active and viable effort behind them before being
considered for Secondary Arch support. This effort has not materialized in
the interim since the current powerpc team dropped ppc32.
There's little point in keeping support for ppc32 support in the kernel
package when it will never be built. This also removes the -smp variant
and with_smp* support, as that was only used on ppc32.